Why do I enjoy it so much?

I like my boyfriend to control me and even beat me. I like to provoke him until he shows me who is in control. I really enjoy it. I like to look in the mirror and see bruises and reddening. No I was never abused as a child or anything, so why do I like it so much? Is it sorta normal for someone to behave like this or am I crazy? Why is this so?